Saikosaponin a mediates the anticonvulsant properties in the HNC models of AE and SE by inhibiting NMDA receptor current and persistent sodium current

Analysis of the action mechanisms and targets of herbal anticonvulsants highlights opportunities for therapeutic engagement with refractory epilepsy

Epilepsy is a neurological disorder characterized by spontaneous and recurring seizures. It poses significant therapeutic challenges due to diverse etiology, pathobiology, and pharmacotherapy-resistant variants. The anticonvulsive effects of herbal leads with biocompatibility and toxicity considerations have attracted much interest, inspiring mechanistic analysis with the view of their use for engagement of new targets and combination with antiseizure pharmacotherapies. This article presents a comprehensive overview of the key molecular players and putative action mechanisms of the most common antiepileptic herbals demonstrated in tissue culture and preclinical models. From the review of the literature, it emerges that their effects are mediated via five distinct mechanisms: (1) reduction of membrane excitability through inhibition of cation channels, (2) improvement of mitochondrial functions with antioxidant effects, (3) enhancement in synaptic transmission mediated by GABAA receptors, (4) improvement of immune response with anti-inflammatory action, and (5) suppression of protein synthesis and metabolism. While some of the primary targets and action mechanisms of herbal anticonvulsants (1, 3) are shared with antiseizure pharmacotherapies, herbal leads also engage with distinct mechanisms (2, 4, and 5), suggesting new drug targets and opportunities for their integration with antiseizure medications. Addressing outstanding questions through research and in silico modeling should facilitate the future use of herbals as auxiliary therapy in epilepsy and guide the development of treatment of pharmacoresistant seizures through rigorous trials and regulatory approval.

Treating Epilepsy with Natural Products: Nonsense or Possibility?

Epilepsy is a neurological disease characterized by recurrent seizures that can lead to uncontrollable muscle twitching, changes in sensitivity to sensory perceptions, and disorders of consciousness. Although modern medicine has effective antiepileptic drugs, the need for accessible and cost-effective medication is urgent, and products derived from plants could offer a solution. For this review, we have focused on natural compounds that have shown anticonvulsant activity in in vivo models of epilepsy at relevant doses. In some cases, the effects have been confirmed by clinical data. The results of our search are summarized in tables according to their molecular targets. We have critically evaluated the data we present, identified the most promising therapeutic candidates, and discussed these in the text. Their perspectives are supported by both pharmacokinetic properties and potential interactions. This review is intended to serve as a basis for future research into epilepsy and related disorders.

A comprehensive review on traditional and modern research of the genus Bupleurum (Bupleurum L., Apiaceae) in recent 10 years

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Bupleurum (family Apiaceae), comprising approximately 248 accepted species, is widely distributed and used in China, Japan, India, Central Asia, North Africa and some European countries as traditional herbal medicines. Certain species have been reported to have significant therapeutic effects in fever, inflammatory disorders, cancer, gastric ulcer, virus infection and other diseases.

AIM OF THE REVIEW

we performed a comprehensive review of the ten-year research progress in phytochemistry, pharmacology, toxicity, along with bibliometrics research of the genus Bupleurum, aiming to identify knowledge gaps for future research.

MATERIALS AND METHODS

All the literatures are retrieved from library and electronic sources including Web of Science, PubMed, Elsevier, Google Scholar, CNKI and Baidu Scholar. These papers cover studies of the traditional use, phytochemistry, pharmacology, and toxicology of the genus Bupleurum.

RESULTS

There is a long history of using the genus Bupleurum in traditional herbal medicine that dated back to over 2000 years ago. Twenty-five species and 8 varieties with 3 variants within this genus have been reported to be effective to treat fever, pain, liver disease, inflammation, thoracolumbar pain, irregular menstruation and rectal prolapse. The main phytochemicals found in these plants are triterpene saponins, volatile oil, flavonoid, lignans, and polysaccharides. Many of these compounds have also been shown to have anti-inflammatory, anti-tumor, antimicrobial, immunoregulation, neuroregulation, hepatoprotective and antidiabetic activities. Meanwhile, improper usage of Bupleurum may induce cytotoxic effects, and polyacetylenes may be the main poisonous compounds.

CONCLUSIONS

This article summarized recent findings about Bupleurum research from many different aspects. While a small number of Bupleurum species have been investigated through modern pharmacology methods, there are still major knowledge gaps due to inadequate studies and ambiguous findings. Future research could focus on more specific phytochemistry studies combined with mechanistic analysis to provide better guidance to utilize Bupleurum as medicinal resources.

A narrative review on traditional Chinese medicine prescriptions and bioactive components in epilepsy treatment

Background and Objective

In traditional Chinese medicine (TCM), natural drugs and their bioactive components have been widely used to treat epilepsy. Epilepsy is a chronic disease caused by abnormal discharge of brain neurons that leads to brain dysfunction and cognitive impairment. Several factors are involved in the mechanisms of epilepsy, and the current treatments do not seem promising. The potential efficacy of natural drugs with lower toxicity and less side effects have attracted increasing attention.

Methods

We used the terms, "TCM", "traditional Chinese medicine", "herbal", "epilepsy", "seizure", and the name of each prescription and bioactive components in the review to collect papers about application of TCM in epilepsy treatment from PubMed online database and Chinese database including Chinese National Knowledge Infrastructure (CNKI), Wanfang, and Weipu.

Key Content and Findings

We summarized some common TCM prescriptions and related active components used for the treatment of epilepsy. Six prescriptions (Chaihu Shugan decoction, Tianma Gouteng decoction, Kangxian capsules, Taohong Siwu decoction, Liujunzi decoction, Compound Danshen dropping pills) and nine main bioactive compounds (Saikosaponin A, Rhynchophylline, Tetramethylpyrazine, Gastrodin, Baicalin and baicalein, α-Asarone, Ginsenoside, Tanshinone, Paeoniflorin) were reviewed to provide a scientific basis for the development of potential antiepileptic drugs (AEDs).

Conclusions

The pharmacological effects and molecular mechanisms of TCM in the treatment of epilepsy are complex, targeting several pathological aspects of epilepsy. However, the limitations of TCM, such as the lack of standardized treatments, have prevented its clinical application in epilepsy treatment. Thus, additional clinical trials are required to further evaluate the effectiveness and safety of TCM prescriptions and their bioactive components in the future.

Pharmacological effects and therapeutic potential of natural compounds in neuropsychiatric disorders: An update

Neuropsychiatric diseases are a group of disorders that cause significant morbidity and disability. The symptoms of psychiatric disorders include anxiety, depression, eating disorders, autism spectrum disorders (ASD), attention-deficit/hyperactivity disorder, and conduct disorder. Various medicinal plants are frequently used as therapeutics in traditional medicine in different parts of the world. Nowadays, using medicinal plants as an alternative medication has been considered due to their biological safety. Despite the wide range of medications, many patients are unable to tolerate the side effects and eventually lose their response. By considering the therapeutic advantages of medicinal plants in the case of side effects, patients may prefer to use them instead of chemical drugs. Today, the use of medicinal plants in traditional medicine is diverse and increasing, and these plants are a precious heritage for humanity. Investigation about traditional medicine continues, and several studies have indicated the basic pharmacology and clinical efficacy of herbal medicine. In this article, we discuss five of the most important and common psychiatric illnesses investigated in various studies along with conventional therapies and their pharmacological therapies. For this comprehensive review, data were obtained from electronic databases such as MedLine/PubMed, Science Direct, Web of Science, EMBASE, DynaMed Plus, ScienceDirect, and TRIP database. Preclinical pharmacology studies have confirmed that some bioactive compounds may have beneficial therapeutic effects in some common psychiatric disorders. The mechanisms of action of the analyzed biocompounds are presented in detail. The bioactive compounds analyzed in this review are promising phytochemicals for adjuvant and complementary drug candidates in the pharmacotherapy of neuropsychiatric diseases. Although comparative studies have been carefully reviewed in the preclinical pharmacology field, no clinical studies have been found to confirm the efficacy of herbal medicines compared to FDA-approved medicines for the treatment of mental disorders. Therefore, future clinical studies are needed to accelerate the potential use of natural compounds in the management of these diseases.

Emerging Promise of Phytochemicals in Ameliorating Neurological Disorders

BACKGROUND

The field of medicine and synthetic drug development have advanced rapidly over the past few decades. However, research on alternative medicine such as phytochemicals cannot be ignored. The main reason for prominent curiosity about phytochemicals stems from the belief that usage of natural compounds is safer and has lesser detrimental side effects.

OBJECTIVE

The aim of the present review was to discuss in detail with several phytochemicals that have been studied or are being studied in the context of various neurological disorders including depression, Alzheimer's disease, Huntington's disease and even neuroinflammatory disorders such as encephalitis.

METHODS

The potential role of phytochemicals in the treatment or management of symptoms associated with neurological disorders have been included in this article. All data included in this paper has been pooled from various databases including Google Scholar, PubMed, Science Direct, Springer and Wiley Online Library.

RESULTS

Phytochemicals have been widely studied for their therapeutic properties associated with neurological disorders. Using various experimental techniques for both in vivo and in vitro experiments, studies have shown that phytochemicals do have antioxidant, anti-inflammatory and neuroprotective activities which play major roles in the treatment of neurological diseases.

CONCLUSION

Even though there has been compelling evidence of the therapeutic role of phytochemicals, further research is still required to evaluate the safety and efficacy of these medicines. Using previously published papers as foundation for additional research such as preclinical studies and clinical trials, phytochemicals can become a safer alternative to synthetic drugs for treating a spectrum of neurological diseases.

Analysis of Medication Rule of Primary Epilepsy Based on Xiaocheng Yan’s Clinical Experience Collection of Epilepsy

Objective

To explore and analyze the medication rule of Professor Xiaocheng Yan in the treatment of primary epilepsy, hoping to provide reference for the clinical treatment of primary epilepsy.

Methods

Mining and analysis of Professor Xiaocheng Yan sorted out the medical cases of primary epilepsy in Xiaocheng Yan's clinical experience collection of epilepsy, extracted the traditional Chinese medicine (TCM) prescription data in the medical cases, standardized the obtained TCM prescription data, and used the data mining function integrated by the ancient and modern medical case cloud platform V2.3.5 to carry out frequency statistics, cluster analysis, association analysis, and complex network analysis on the TCM data, and the common herbs used by Professor Xiaocheng Yan in the treatment of primary epilepsy, properties and classifications of commonly used herbs, pairs of commonly used herbs, and core prescriptions were obtained.

Results

A total of 39 cases, 228 medical records, and 230 prescriptions data of TCM were included. A total of 96 Chinese medicinal herbs were involved, and the total frequency of medication was 3,828. High-frequency herbs include Rhizoma Gastrodiae (Tianma) (222 times), Ramulus Uncariae cum Uncis (Gouteng) (220 times), Rhizoma Acori Tatarinowii (Shichangpu) (216 times), Rhizoma Pinelliae Praeparatum (Fabanxia) (207 times), Bombyx Batryticatus (Jiangcan) (206 times), and Periostracum Cicadae (Chantui) (181 times). The main properties and flavors of commonly used Chinese medicinal herbs were sweet, bitter, and pungent, which were mainly attributed to the four meridians of liver, lung, heart, and spleen. Commonly used couplet herbs were {Periostracum Cicadae (Chantui)} ≥ {Bombyx Batryticatus (Jiangcan)}, {Rhizoma Acori Tatarinowii (Shichangpu)} ≥{ Bombyx Batryticatus (Jiangcan)}, {Radix Bupleuri (Chaihu)} ≥ {Radix Scutellariae (Huangqin)}, {Rhizoma Gastrodiae (Tianma)} ≥ {Ramulus Uncariae cum Uncis (Gouteng)}, {Rhizoma Acori Tatarinowii (Shichangpu)} ≥ {Periostracum Cicadae (Chantui)}, {Ramulus Uncariae cum Uncis (Gouteng)} ≥ {Bombyx Batryticatus (Jiangcan)}, {Bombyx Batryticatus (Jiangcan)} ≥ {Rhizoma Gastrodiae (Tianma)}, {Rhizoma Acori Tatarinowii (Shichangpu)} ≥ {Ramulus Uncariae cum Uncis (Gouteng)}, etc. The core prescription composition was based on the addition and subtraction of Tianma Gouteng decoction and Erchen decoction. The main pharmacological mechanisms of core prescriptions are mainly reflected in antioxidation, enhancing GABA efficacy, and regulating NMDA channel and sodium channel, neuroprotection, and so on.

Conclusion

Professor Xiaocheng Yan's medication for the treatment of primary epilepsy was based on the principle of relieving wind and spasm, drying dampness and resolving phlegm, giving consideration to both Qi and blood, and harmonizing liver, lung, heart, and spleen.

Saikosaponins: A Review of Structures and Pharmacological Activities

Radix Bupleuri is a traditional medicine widely used in China and other Asian countries. Phytochemistry and pharmacology study reveal that saikosaponins(SSs) are the main bioactive compounds in Radix Bupleuri. SSs are complex compounds composed of triterpene aglycone and carbohydrate part containing 1-13 monosaccharides, which can be divided into seven types based on their structural characteristics. Many different kinds of SSs have been isolated from plants of Bupleurum L. SSs show a variety of biological activities, such as central nervous system protection, liver protection, antivirus, anti-tumor, anti-inflammation, hormone-like effects, and immune regulation functions. Due to their broad activity and favorable safety profile, SSs attract an increasing amount of attention in recent years. In this review, the structures of 86 SSs are summarized based on the different aglycones due to the diverse structures of saikosaponin(SS). The pharmacological effects and related mechanism of SSs are thoroughly reviewed, and perspectives for future research are further discussed.

Chinese Herbal Medicine for Treating Epilepsy

Chinese herbal medicine has a long history of use for treating epilepsy. Because of the side effects of Western antiepileptic therapy and the quest for more accessible treatment, complementary and alternative medicines have become popular. Traditional Chinese medical diet therapy appears to be safe and effective. We searched PubMed and the Cochrane Library through November 2020 for the use of traditional Chinese medicine in clinical settings, including plants, fungi, and animals. Combinations of keywords included “epilepsy,” “seizure,” “antiepileptic,” “anticonvulsive,” “Chinese herbal medicine,” “Chinese herb,” and each of the Latin names, English names, and scientific names of herbs. We also summarized the sources and functions of these herbs in Chinese medicine. Different herbs can be combined to increase antiepileptic effects through various mechanisms, including anti-inflammation, antioxidation, GABAergic effect enhancement, modulation of NMDA channels and sodium channel, and neuroprotection. Despite reports of their anticonvulsive effects, adequate experimental evidence and randomized controlled clinical trials are required to confirm their antiepileptic effects.

Potential anti-epileptic phytoconstituents: An updated review

ETHNOPHARMACOLOGICAL RELEVANCE

Epilepsy is one of the most commonly occurring non-communicable neurological disorder that affects people of all age groups. Around 50 million people globally are epileptic, with 80% cases in developing countries due to lack of access to treatments determined by high cost and poor availability or it can be defined by the fraction of active epileptic patients who are not appropriately being treated. The availability of antiepileptic drugs and their adjuvant therapy in such countries is less than 50% and these are highly susceptible to drug interactions and severe adverse effects. As a result, the use of herbal medicine is increasingly becoming popular.

AIM OF THE STUDY

To provide pharmacological information on the active constituents evaluated in the preclinical study to treat epilepsy with potential to be used as an alternative therapeutic option in future. It also provides affirmation for the development of novel antiepileptic drugs derived from medicinal plants.

MATERIALS AND METHODS

Relevant information on the antiepileptic potential of phytoconstituents in the preclinical study (in-vitro, in-vivo) is provided based on their effect on screening parameters. Besides, relevant information on pharmacology of phytoconstituents, the traditional use of their medicinal plants related to epilepsy and status of phytoconstituents in the clinical study were derived from online databases, including PubMed, Clinicaltrial. gov, The Plant List (TPL, www.theplantlist.org), Science Direct. Articles identified using preset searching syntax and inclusion criteria are presented.

RESULTS

More than 70% of the phytoconstituents reviewed in this paper justified the traditional use of their medicinal plant related to epilepsy by primarily acting on the GABAergic system. Amongst the phytoconstituents, only cannabidiol and tetrahydrocannabinol have been explored for clinical application in epilepsy.

CONCLUSION

The preclinical and clinical data of the phytoconstituents to treat epilepsy and its associated comorbidities provides evidence for the discovery and development of novel antiepileptic drugs from medicinal plants. In terms of efficacy and safety, further randomized and controlled clinical studies are required to understand the complete pharmacodynamic and pharmacokinetic picture of phytoconstituents. Also, specific botanical source evaluation is needed.

Natural Medicines for the Treatment of Epilepsy: Bioactive Components, Pharmacology and Mechanism

Epilepsy is a chronic disease that can cause temporary brain dysfunction as a result of sudden abnormal discharge of the brain neurons. The seizure mechanism of epilepsy is closely related to the neurotransmitter imbalance, synaptic recombination, and glial cell proliferation. In addition, epileptic seizures can lead to mitochondrial damage, oxidative stress, and the disorder of sugar degradation. Although the mechanism of epilepsy research has reached up to the genetic level, the presently available treatment and recovery records of epilepsy does not seem promising. Recently, natural medicines have attracted more researches owing to their low toxicity and side-effects as well as the excellent efficacy, especially in chronic diseases. In this study, the antiepileptic mechanism of the bioactive components of natural drugs was reviewed so as to provide a reference for the development of potential antiepileptic drugs. Based on the different treatment mechanisms of natural drugs considered in this review, it is possible to select drugs clinically. Improving the accuracy of medication and the cure rate is expected to compensate for the shortage of the conventional epilepsy treatment drugs.

Zebrafish-Based Screening of Antiseizure Plants Used in Traditional Chinese Medicine: Magnolia officinalis Extract and Its Constituents Magnolol and Honokiol Exhibit Potent Anticonvulsant Activity in a Therapy-Resistant Epilepsy Model

With the aim to discover interesting lead compounds that could be further developed into compounds active against pharmacoresistant epilepsies, we first collected 14 medicinal plants used in traditional Chinese medicine (TCM) against epilepsy. Of the six extracts that tested positive in a pentylenetetrazole (PTZ) behavioral zebrafish model, only the ethanol and acetone extracts from Magnolia officinalis (M. officinalis) also showed effective antiseizure activity in the ethylketopentenoate (EKP) zebrafish model. The EKP model is regarded as an interesting discovery platform to find mechanistically novel antiseizure drugs, as it responds poorly to a large number of marketed anti-epileptics. We then demonstrated that magnolol and honokiol, two major constituents of M. officinalis, displayed an effective behavioral and electrophysiological antiseizure activity in both the PTZ and the EKP models. Out of six structural analogues tested, only 4-O-methylhonokiol was active and to a lesser extent tetrahydromagnolol, whereas the other analogues (3,3'-dimethylbiphenyl, 2,2'-biphenol, 2-phenylphenol, and 3,3',5,5'-tetra-tert-butyl-[1,1'-biphenyl]-2,2'-diol) were not consistently active in the aforementioned assays. Finally, magnolol was also active in the 6 Hz psychomotor mouse model, an acute therapy-resistant rodent model, thereby confirming the translation of the findings from zebrafish larvae to mice in the field of epilepsy. We also developed a fast and automated power spectral density (PSD) analysis of local field potential (LFP) recordings. The PSD results are in agreement with the visual analysis of LFP recordings using Clampfit software and manually counting the epileptiform events. Taken together, screening extracts of single plants employed in TCM, using a combination of zebrafish- and mouse-based assays, allowed us to identify allyl biphenol as a chemical scaffold for the future development of compounds with potential activity against therapy-resistant epilepsies.

Saikosaponin d causes apoptotic death of cultured neocortical neurons by increasing membrane permeability and elevating intracellular Ca2+ concentration

Saikosaponins (SSs) are a class of naturally occurring oleanane-type triterpenoid saponins found in Radix bupleuri that has been widely used in traditional Chinese medicine. As the main active principals of Radix bupleuri, SSs have been shown to suppress mouse motor activity, impair learning and memory, and decrease hippocampal neurogenesis. In the present study, we investigated the effect of five SSs (SSa, SSb1, SSb2, SSc, and SSd) on neuronal viability and the underlying mechanisms in cultured murine neocortical neurons. We demonstrate that SSa, SSb1 and SSd produce concentration-dependent apoptotic neuronal death and induce robust increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i) at low micromolar concentrations with a rank order of SSd > SSa > SSb1, whereas SSb2 and SSc have no detectable effect on both neuronal survival and [Ca²⁺]_i. Mechanistically, SSd-induced elevation in [Ca²⁺]_i is the primary result of enhanced extracellular Ca²⁺ influx, which likely triggers Ca²⁺-induced Ca²⁺ release through ryanodine receptor activation, but not SERCA inhibition. SSd-induced Ca²⁺ entry occurs through a non-selective mechanism since blockers of major neuronal Ca²⁺ entry pathways, including L-type Ca²⁺ channel, NMDA receptor, AMPA receptor, Na⁺-Ca²⁺ exchanger, and TRPV1, all failed to attenuate the Ca²⁺ response to SSd. Further studies demonstrate that SSd increases calcein efflux and induces an inward current in neocortical neurons. Together, these data demonstrate that SSd elevates [Ca²⁺]_i due to its ability to increase membrane permeability, likely by forming pores in the surface of membrane, which leads to massive Ca²⁺ influx and apoptotic neuronal death in neocortical neurons.

A comprehensive review and perspectives on pharmacology and toxicology of saikosaponins

BACKGROUND

Radix Bupleuri (RB) has been widely used in Chinese Traditional Medicine for over 2000 years and is currently marketed in China as Chai-Hu-Shu-Gan tablets and Xiao-Yao-Wan tablets. Saikosaponins (SSs, especially SSa, SSc and SSd), as the major bioactive compounds in RB, represent anti-inflammatory, anti-tumor, anti-oxidant, anti-viral and hepatoprotective effects.

PURPOSE

To summarize recent findings regarding to the extraction, detection, biosynthesis, metabolism, pharmacological/toxicological effects of SSs.

METHODS

Online academic databases (including PubMed, Google Scholar, Web of Science and CNKI) were searched using search terms of "Saikosaponin", "Radix Bupleuri", "Bupleurum" and combinations to include published studies of SSs primarily from 2003 to 2018. Several critical previous studies beyond this period were also included.

RESULTS

354 papers were found and 165 papers were reviewed. SSs have drawn great attention for their anti-inflammation, anti-viral and anti-cancer effects and contradictory roles in the regulation of cell apoptosis, oxidative stress and liver fibrosis. Meanwhile, increased risks of overdose-induced acute or accumulation-related chronic hepatotoxicity of SSs and RB have also been reported. However, underlying mechanisms of SSs bioactivities, the metabolism of SSs and bioactivities of SSs metabolites are largely unknown.

CONCLUSION

This comprehensive review of SSs provides novel insights and perspectives on the limitations of current studies and the importance of metabolism study and the dose-pharmacological/toxic relationship of SSs for the future discovery of SSs-based therapeutic strategies and clinical safe practice.

A comprehensive review and perspectives on pharmacology and toxicology of saikosaponins

BACKGROUND

Radix Bupleuri (RB) has been widely used in Chinese Traditional Medicine for over 2000 years and is currently marketed in China as Chai-Hu-Shu-Gan tablets and Xiao-Yao-Wan tablets. Saikosaponins (SSs, especially SSa, SSc and SSd), as the major bioactive compounds in RB, represent anti-inflammatory, anti-tumor, anti-oxidant, anti-viral and hepatoprotective effects.

PURPOSE

To summarize recent findings regarding to the extraction, detection, biosynthesis, metabolism, pharmacological/toxicological effects of SSs.

METHODS

Online academic databases (including PubMed, Google Scholar, Web of Science and CNKI) were searched using search terms of "Saikosaponin", "Radix Bupleuri", "Bupleurum" and combinations to include published studies of SSs primarily from 2003 to 2018. Several critical previous studies beyond this period were also included.

RESULTS

354 papers were found and 165 papers were reviewed. SSs have drawn great attention for their anti-inflammation, anti-viral and anti-cancer effects and contradictory roles in the regulation of cell apoptosis, oxidative stress and liver fibrosis. Meanwhile, increased risks of overdose-induced acute or accumulation-related chronic hepatotoxicity of SSs and RB have also been reported. However, underlying mechanisms of SSs bioactivities, the metabolism of SSs and bioactivities of SSs metabolites are largely unknown.

CONCLUSION

This comprehensive review of SSs provides novel insights and perspectives on the limitations of current studies and the importance of metabolism study and the dose-pharmacological/toxic relationship of SSs for the future discovery of SSs-based therapeutic strategies and clinical safe practice.

A comprehensive review and perspectives on pharmacology and toxicology of saikosaponins

BACKGROUND

Radix Bupleuri (RB) has been widely used in Chinese Traditional Medicine for over 2000 years and is currently marketed in China as Chai-Hu-Shu-Gan tablets and Xiao-Yao-Wan tablets. Saikosaponins (SSs, especially SSa, SSc and SSd), as the major bioactive compounds in RB, represent anti-inflammatory, anti-tumor, anti-oxidant, anti-viral and hepatoprotective effects.

PURPOSE

To summarize recent findings regarding to the extraction, detection, biosynthesis, metabolism, pharmacological/toxicological effects of SSs.

METHODS

Online academic databases (including PubMed, Google Scholar, Web of Science and CNKI) were searched using search terms of "Saikosaponin", "Radix Bupleuri", "Bupleurum" and combinations to include published studies of SSs primarily from 2003 to 2018. Several critical previous studies beyond this period were also included.

RESULTS

354 papers were found and 165 papers were reviewed. SSs have drawn great attention for their anti-inflammation, anti-viral and anti-cancer effects and contradictory roles in the regulation of cell apoptosis, oxidative stress and liver fibrosis. Meanwhile, increased risks of overdose-induced acute or accumulation-related chronic hepatotoxicity of SSs and RB have also been reported. However, underlying mechanisms of SSs bioactivities, the metabolism of SSs and bioactivities of SSs metabolites are largely unknown.

CONCLUSION

This comprehensive review of SSs provides novel insights and perspectives on the limitations of current studies and the importance of metabolism study and the dose-pharmacological/toxic relationship of SSs for the future discovery of SSs-based therapeutic strategies and clinical safe practice.

A comprehensive review and perspectives on pharmacology and toxicology of saikosaponins

BACKGROUND

Radix Bupleuri (RB) has been widely used in Chinese Traditional Medicine for over 2000 years and is currently marketed in China as Chai-Hu-Shu-Gan tablets and Xiao-Yao-Wan tablets. Saikosaponins (SSs, especially SSa, SSc and SSd), as the major bioactive compounds in RB, represent anti-inflammatory, anti-tumor, anti-oxidant, anti-viral and hepatoprotective effects.

PURPOSE

To summarize recent findings regarding to the extraction, detection, biosynthesis, metabolism, pharmacological/toxicological effects of SSs.

METHODS

Online academic databases (including PubMed, Google Scholar, Web of Science and CNKI) were searched using search terms of "Saikosaponin", "Radix Bupleuri", "Bupleurum" and combinations to include published studies of SSs primarily from 2003 to 2018. Several critical previous studies beyond this period were also included.

RESULTS

354 papers were found and 165 papers were reviewed. SSs have drawn great attention for their anti-inflammation, anti-viral and anti-cancer effects and contradictory roles in the regulation of cell apoptosis, oxidative stress and liver fibrosis. Meanwhile, increased risks of overdose-induced acute or accumulation-related chronic hepatotoxicity of SSs and RB have also been reported. However, underlying mechanisms of SSs bioactivities, the metabolism of SSs and bioactivities of SSs metabolites are largely unknown.

CONCLUSION

This comprehensive review of SSs provides novel insights and perspectives on the limitations of current studies and the importance of metabolism study and the dose-pharmacological/toxic relationship of SSs for the future discovery of SSs-based therapeutic strategies and clinical safe practice.

Saikosaponin A modulates remodeling of Kv4.2-mediated A-type voltage-gated potassium currents in rat chronic temporal lobe epilepsy

Background

Chronic temporal lobe epilepsy (cTLE) is the most common intractable epilepsy. Recent studies have shown that saikosaponin A (SSa) could inhibit epileptiform discharges induced by 4 action potentials and selectively increase the transient inactivating K⁺ currents (I_A). However, the mechanisms of SSa on I_A remain unclear. In this study, we comprehensively evaluated the anticonvulsant activities of SSa and explored whether or not it plays an anti-epileptic role in a Li-pilocarpine induced epilepsy rat model via remodeling Kv4.2-mediated A-type voltage-gated potassium currents (Kv4.2-mediated I_A).

Materials and methods

All in vitro spontaneous recurrent seizures (SRS) were recorded with continuous video monitoring. Nissl’s staining was used to evaluate the SSa protection of neurons and immunohistochemistry, Western blot, and quantitative reverse transcription PCR were used to quantify the expression of Kchip1 and Kv4.2 in the hippocampal CA1 field and the adjacent cortex following Li-pilocarpine induced status epilepticus. We used whole-cell current-clamp recordings to evaluate the anticonvulsant activities of SSa in a hippocampal neuronal culture model of cTLE, while whole-cell voltage-clamp recordings were used to evaluate the modulatory effects of SSa on Kv4.2-mediated I_A.

Results

SSa treatment significantly reduced the frequency and duration of SRS over the course of eight weeks and increased the production of Kchip1 and Kv4.2. In addition, SSa attenuated spontaneous recurrent epileptiform discharges (SREDs) in the hippocampal neuronal model and up-regulated Kv4.2-mediated I_A.

Conclusions

SSa exerted a disease-modifying effect in our cTLE rat model both in vivo and in vitro; the increase in Kv4.2-mediated I_A may contribute to the anticonvulsant mechanisms of SSa.

Excavating Anticonvulsant Compounds from Prescriptions of Traditional Chinese Medicine in the Treatment of Epilepsy

Traditional Chinese medicine (TCM) has a long history and been widely used in prevention and treatment of epilepsy in China. This paper is intended to review the advances in the active anticonvulsant compounds isolated from herbs in the prescription of TCM in the treatment of epilepsy. These compounds were introduced with the details including classification, CAS number specific structure and druggability data. Meanwhile, much of the research in these compounds in the last two decades has shown that they exhibited favorable pharmacological properties in treatment of epilepsy both in in vivo and in vitro models. In addition, in this present review, the evaluation of the effects of the anticonvulsant classical TCM prescriptions is discussed. According to these rewarding pharmacological effects and chemical substances, the prescription of TCM herbs could be an effective therapeutic strategy for epilepsy patients, and also could be a promising source for the development of new drugs.

Saikosaponins: a review of pharmacological effects

Over the past decades, a number of phytochemicals have been reported to possess potent pharmacological effects. Saikosaponins represent a group of oleanane derivatives, usually as glucosides, which are commonly found in medicinal plants Bupleurum spp., which have been used as traditional Chinese medicine for more than 1,000 years in China. Emerging evidence suggests that saikosaponins have many pharmacological effects, including sedation, anticonvulsant, antipyretic, antiviral, immunity, anti-inflammation, antitumor properties, protecting liver and kidney and so on. The present review provides a comprehensive summary and analysis of the pharmacological properties of saikosaponins, supporting the potential uses of saikosaponins as a medicinal agent.

A systematic review of the active saikosaponins and extracts isolated from Radix Bupleuri and their applications

CONTEXT

Radix Bupleuri has been used in traditional Chinese medicine for over 2000 years with functions of relieving exterior syndrome, clearing heat, regulating liver-qi, and lifting yang-qi. More natural active compounds, especially saikosaponins, have been isolated from Radix Bupleuri, which possess various valuable pharmacological activities.

OBJECTIVE

To summarize the current knowledge on pharmacological activities, mechanisms and applications of extracts and saikosaponins isolated from Radix Bupleuri, and obtain new insights for further research and development of Radix Bupleuri.

METHODS

PubMed, Web of Science, Science Direct, Research Gate, Academic Journals and Google Scholar were used as information sources through the inclusion of the search terms 'Radix Bupleuri', 'Bupleurum', 'saikosaponins', 'Radix Bupleuri preparation', and their combinations, mainly from the year 2008 to 2016 without language restriction. Clinical preparations containing Radix Bupleuri were collected from official website of China Food and Drug Administration (CFDA).

RESULTS AND CONCLUSION

296 papers were searched and 128 papers were reviewed. A broad spectrum of in vitro and in vivo research has proved that Radix Bupleuri extracts, saikosaponin a, saikosaponin d, saikosaponin c, and saikosaponin b₂, exhibit evident anti-inflammatory, antitumor, antiviral, anti-allergic, immunoregulation, and neuroregulation activities mainly through NF-κB, MAPK or other pathways. 15 clinical preparations approved by CFDA remarkably broaden the application of Radix Bupleuri. The main side effect of Radix Bupleuri is liver damage when the dosage is excess, which indicates that the maximum tolerated dose is critical for clinical use of Radix Bupleuri extract and purified compounds.

Stimulation of Osteogenic Differentiation by Saikosaponin-A in Bone Marrow Stromal Cells Via WNT/β-Catenin Pathway

Saikosaponin-A (SA), a class of native compound with numerous biological activities, may exert protective effect against postmenopausal bone loss. However, it remains unknown whether SA regulates the osteogenic differentiation of bone marrow stromal cells (BMSCs) in the treatment and prevention of osteoporosis. In this study, BMSCs were treated with various concentrations of SA to stimulate osteogenic differentiation over a 14-day period. Additionally, a canonical ovariectomized (OVX) mouse model was used to evaluate the effect of 3-month SA treatment in preventing postmenopausal osteoporosis. In vitro, we found that SA promotes alkaline phosphatase activity/staining and Alizarin red assay, stimulated the expression of osteogenic markers, i.e., runt-related transcription factor 2 (Runx2), osterix, osteopontin, and osteocalcin (OCN) in BMSCs. In vivo, the trabecular number, trabecular thickness, and trabecular bone mineral density of the distal femoral metaphysis were significantly increased in OVX mice treated intraperitoneally with SA for 3 months compared with OVX mice that not treated with SA. Moreover, the expression of Runx2 and OCN in OVX + SA mice was significantly increased than that in OVX mice. Finally, we found that SA activated the WNT/β-catenin pathway and the expression of several downstream genes including T-cell factor-1 and lymphoid enhancer factor-1. Inhibition of WNT/β-catenin pathway by Dickkopf-related protein 1 blocked the positive role of SA on osteogenesis. Therefore, SA promoted the osteogenic differentiation of BMSCs through WNT/β-catenin signaling.

Saikosaponin A Alleviates Symptoms of Attention Deficit Hyperactivity Disorder through Downregulation of DAT and Enhancing BDNF Expression in Spontaneous Hypertensive Rats

The disturbed dopamine availability and brain-derived neurotrophic factor (BDNF) expression are due in part to be associated with attention deficit hyperactivity disorder (ADHD). In this study, we investigated the therapeutical effect of saikosaponin a (SSa) isolated from Bupleurum Chinese DC, against spontaneously hypertensive rat (SHR) model of ADHD. Methylphenidate and SSa were orally administered for 3 weeks. Activity was assessed by open-field test and Morris water maze test. Dopamine (DA) and BDNF were determined in specific brain regions. The mRNA or protein expression of tyrosine hydroxylase (TH), dopamine transporter (DAT), and vesicles monoamine transporter (VMAT) was also studied. Both MPH and SSa reduced hyperactivity and improved the spatial learning memory deficit in SHRs. An increased DA concentration in the prefrontal cortex (PFC) and striatum was also observed after treating with the SSa. The increased DA concentration may partially be attributed to the decreased mRNA and protein expression of DAT in PFC while SSa exhibited no significant effects on the mRNA expression of TH and VMAT in PFC of SHRs. In addition, BDNF expression in SHRs was also increased after treating with SSa or MPH. The obtained result suggested that SSa may be a potential drug for treating ADHD.

Gastrodin Reduces the Severity of Status Epilepticus in the Rat Pilocarpine Model of Temporal Lobe Epilepsy by Inhibiting Nav1.6 Sodium Currents

Temporal lobe epilepsy (TLE) is one of the most refractory types of adult epilepsy, and treatment options remain unsatisfactory. Gastrodin (GAS), a phenolic glucoside used in Chinese herbal medicine and derived from Gastrodia elata Blume, has been shown to have remarkable anticonvulsant effects on various models of epilepsy in vivo. However, the mechanisms of GAS as an anticonvulsant drug remain to be established. By utilizing a combination of behavioral surveys, immunofluorescence and electrophysiological recordings, the present study characterized the anticonvulsant effect of GAS in a pilocarpine-induced status epilepticus (SE) rat model of TLE and explored the underlying cellular mechanisms. We found that GAS pretreatment effectively reduced the severity of SE in the acute phase of TLE. Moreover, GAS protected medial entorhinal cortex (mEC) layer III neurons from neuronal death and terminated the SE-induced bursting discharge of mEC layer II neurons from SE-experienced rats. Furthermore, the current study revealed that GAS prevented the pilocarpine-induced enhancement of Nav1.6 currents (persistent (I_NaP) and resurgent (I_NaR) currents), which were reported to play a critical role in the generation of bursting spikes. Consistent with this result, GAS treatment reversed the expression of Nav1.6 protein in SE-experienced EC neurons. These results suggest that the inhibition of Nav1.6 sodium currents may be the underlying mechanism of GAS's anticonvulsant properties.

Identification and Characterization of Two New Degradation Products of Saikosaponin A under Acid Hydrolytic Conditions

Saikosaponin (SS) A is a compound with various pharmacological properties and is easily degraded into SS-B1 and SS-G under acid conditions. In the present work, two new degradation products of SS-A, formed under acid hydrolytic conditions, were detected and isolated using analytical and semi-preparative liquid chromatography technology; furthermore, their structures were characterized as hydroxy-saikosaponin A and SS-B2 by spectral analysis, which is not only essential in stability-indicating method development and validation, but also could be used as a worst case scenario to assess the analytical method performance of SS-A. Moreover, their structural transformation pathways are also proposed.

Protective Effects of Otophylloside N on Pentylenetetrazol-Induced Neuronal Injury In vitro and In vivo

Approximately 30% of epileptic patients worldwide are medically unable to control their seizures. In addition, repeated epileptic seizures generally lead to neural damage. Pentylenetetrazol (PTZ) is a clinical circulatory and respiratory stimulant that is experimentally used to mimic epileptic convulsion in epilepsy research. Here, we systematically explore the neuroprotective effects of a pure compound isolated from Cynanchum otophyllum Schneid (Qingyangshen), Otophylloside N (OtoN), against PTZ-induced neuronal injury. We used three models: in vitro primary cortical neurons, in vivo mice, and in vivo zebrafish. Our results revealed that OtoN treatment may attenuate PTZ-induced morphology changes, cell death, LDH efflux in embryonic neuronal cells of C57BL/6J mice, and convulsive behavior in zebrafish. Additionally, our Western blot and RT-PCR results demonstrated that OtoN may attenuate PTZ-induced apoptosis and neuronal activation in neuronal cells, mice, and zebrafish. OtoN may reduce PTZ-induced cleavage of poly ADP-ribose polymerase and upregulation of the Bax/Bcl-2 ratio and decrease the expression level of c-Fos. This study is the first investigation of the neuroprotective effects of OtoN, which might be developed as a novel antiepileptic drug.

Saikosaponin a functions as anti-epileptic effect in pentylenetetrazol induced rats through inhibiting mTOR signaling pathway

OBJECTIVE

Saikosaponin a (SSa), which is one major bioactive compound isolated from radix bupleuri, has been demonstrated to exhibit the properties of anticonvulsant and antiepileptic in few reports. This study aims to clarify the molecular mechanism by which SSa protects against pentylenetetrazol (PTZ) induced epileptic seizure.

METHODS

PTZ induced rat and hippocampal neuron were established. Treated rats or hippocampal neuron with SSa, and mTOR, P70S6K, IL-1β and TNF-α were then determined.

RESULTS

In PTZ induced rat, SSa significantly reduced seizure severity and duration while markedly elevated seizure latency, and it also down-regulated hippocampal p-mTOR, p-70S6K, L-1β and TNF-α expression. In hippocampal neurons exposed to PTZ, p-mTOR and p-70S6K expression levels were also decreased by SSa. Pre-incubated hippocampal neurons with leucine, an mTOR agonist, reversed the effects of SSa on decreasing cytokines expression and inhibiting cell apoptosis. The treatment of mTOR inhibitor rapamycin prevented against the increase of cytokines expression and hippocampal neuron apoptosis induced by PTZ. Leucine also canceled the alleviation of seizures and induction of hippocampal caspase-3 activity in PTZ induced rat with the treatment of SSa.

CONCLUSION

SSa protects against PTZ induced epileptic seizure and hippocampal neuron apoptosis through inhibiting mTOR signaling pathway.

Saikosaponin a protects TBI rats after controlled cortical impact and the underlying mechanism

The inflammatory response plays a significant role in neuronal cell death and functional deficits after Traumatic brain injury (TBI). Importantly, anti-inflammatory agents have neuroprotective effects. To date, however, no studies have investigated the neuroprotective effects of Saikosaponin a (SSa) after TBI. In the present study, rats with controlled cortical impact (CCI) were used to investigate the neuroprotective effects of SSa. The results showed that SSa reduced body weight loss, improved neurological functions andcognition, and reduced brain edema and blood brain barrier permeability after CCI. Moreover, SSa inhibited aquaporin-4 (AQP-4), matrix metalloprotein-9 (MMP-9), mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (c-JNK), tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). The reduction in the loss of occludin mediated by SSa may partially account for its neuroprotective effects. Together, our results suggest that SSa appears to counteract the inflammatory response and neurological function deficits after TBI and possibly via an anti-inflammatory response and inhibition of the MAPK signaling pathway.

Review of the use of botanicals for epilepsy in complementary medical systems--Traditional Chinese Medicine

In traditional Chinese medicine, botanical remedies have been used for centuries to treat seizures. This review aimed to summarize the botanicals that have been used in traditional Chinese medicine to treat epilepsy. We searched Chinese online databases to determine the botanicals used for epilepsy in traditional Chinese medicine and identified articles using a preset search syntax and inclusion criteria of each botanical in the PubMed database to explore their potential mechanisms. Twenty-three botanicals were identified to treat epilepsy in traditional Chinese medicine. The pharmacological mechanisms of each botanical related to antiepileptic activity, which were mainly examined in animal models, were reviewed. We discuss the use and current trends of botanical treatments in China and highlight the limitations of botanical epilepsy treatments. A substantial number of these types of botanicals would be good candidates for the development of novel AEDs. More rigorous clinical trials of botanicals in traditional Chinese medicine for epilepsy treatment are encouraged in the future. This article is part of a Special Issue entitled "Botanicals for Epilepsy".

Saikosaponin a Enhances Transient Inactivating Potassium Current in Rat Hippocampal CA1 Neurons

Saikosaponin a (SSa), a main constituent of the Chinese herb Bupleurum chinense DC., has been demonstrated to have antiepileptic activity. Recent studies have shown that SSa could inhibit NMDA receptor current and persistent sodium current. However, the effects of SSa on potassium (K⁺) currents remain unclear. In this study, we tested the effect of SSa on 4AP-induced epileptiform discharges and K⁺ currents in CA1 neurons of rat hippocampal slices. We found that SSa significantly inhibited epileptiform discharges frequency and duration in hippocampal CA1 neurons in the 4AP seizure model in a dose-dependent manner with an IC₅₀ of 0.7 μM. SSa effectively increased the amplitude of I_Total and I_A, significantly negative-shifted the activation curve, and positive-shifted steady-state curve of I_A. However, SSa induced no significant changes in the amplitude and activation curve of I_K. In addition, SSa significantly increased the amplitude of 4AP-sensitive K⁺ current, while there was no significant change in the amplitude of TEA-sensitive K⁺ current. Together, our data indicate that SSa inhibits epileptiform discharges induced by 4AP in a dose-dependent manner and that SSa exerts selectively enhancing effects on I_A. These increases in I_A may contribute to the anticonvulsant mechanisms of SSa.